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plofioRS, and detonations, far more violent 

 than thofe occafioned by the elaftic gafes 

 before mentioned. Thus, if a cannon, after 

 having been fired feverai times, be fpunged 

 with a wet rammer which too exadily fits 

 the calibre, the vapour produced at the bot- 

 tom of the cannon, unable to efcape as it 

 expands, will force the rammer out with 

 fuch violence as fometimes to carry away 

 the arm of the gunner. If a fmall quan- 

 tity of water be inclofed in a globe of iron, 

 or any other metal, fo that the vapour 

 cannot efcape, and the globe be expofed 

 to a ftrong fire, it will foon buril with 

 a loud noife, ia the fame manner as if the 

 explofion had been caufed by gunpowder. 



But nothing, in my opinion, more aptly 

 (hows the nature of the de(lrud:ive explo- 

 iions which volcanos may produce by the 

 evaporation of water, than the fatal acci- 

 dents which fometimes happen in confe- 

 quence of pouring melted metals into 

 moulds not fufficiently dried. An account 

 of cue of this kind may be found in the 



fourth 



